OVERALL SUMMARY The mission of the OPTICC (Optimizing Implementation in Cancer Control) Center is to improve cancer outcomes by supporting optimized implementation of evidence-based interventions (EBIs) in cancer control. Optimized implementation occurs when: (1) the strategies employed to implement EBIs address the key barriers to implementation that are active in the specific settings in which implementation occurs, and (2) those strategies reflect the best possible methods for addressing the barriers. Despite two decades of progress in implementation science (IS), practical tools and guidance to support optimized EBI implementation are lacking; as a result, strategies are often mismatched to barriers and are often not optimized for effectiveness, efficiency, or fit with local resources. The result is suboptimal implementation in the form of lost time, effort, and resources and, ultimately, poorer cancer outcomes. The OPTICC Center will advance IS and, in turn, improve EBI implementation in cancer control by developing, testing, and refining innovative methods for optimizing EBI implementation. The OPTICC Center is a strategic collaboration of the University of Washington (UW), Kaiser Permanente Washington Health Research Institute (KPWHRI), and the Fred Hutchinson Cancer Research Center (FHCRC). Three cores will support its work. The Administrative Core will promote multidisciplinary collaboration, research excellence, and methodological innovation. It will also lead Center outreach and dissemination efforts, evaluate Center impact, and coordinate Center activities. The Research Program Core will conduct innovative implementation studies, method and measurement studies, and small pilot studies that advance the Center?s ?grand challenge? IS theme of optimizing EBI implementation. A three-stage approach to optimizing EBI implementation will be taken?identify and prioritize barriers, match strategies, and test strategies?with measurement development spanning all three stages. The Implementation Laboratory Core will establish and coordinate a network of diverse clinical and community sites to conduct ?in vivo? IS studies, implement cancer control EBIs, and shape the Center?s research agenda. The Center?s initial studies will focus on optimizing implementation of screening EBIs for cervical, colorectal, breast, and ovarian cancer. However, the methods for optimizing EBI implementation that the Center will develop, test, and refine can be applied broadly across the cancer care continuum, for a wide range of cancers, to answer a wide range of IS questions.